The present invention relates to a new and improved method of decreasing the width of a continuously cast strand, especially a steel strand, wherein at least a short or narrow side of an adjustable mold can be moved during the continuous casting operation.
There has already become known to the art an accepted method wherein there is used a continuous casting mold having a short or narrow side which is divided into an upper part and a lower part. During change in the width of the cast strand, the upper non-imbued or non-wetted part is adjusted to a desired extent or position and the withdrawal of the steel strand as well as the oscillation device for the mold is stopped. The bath level in the mold ascends until arriving at the upper part of the mold. After there has been formed an adequate skin or shell thickness at the cast strand or casting, during which time the infeed of the melt to the mold at least must be throttled, the lower mold part, as soon as such is possible is adjusted and the withdrawal of the cast strand can proceed. What is particularly disadvantageous with this technique is that due to stopping the movement of the steel strand there is undesirably altered the cooling conditions, something which is unsatisfactory from the metallurgical standpoint, because then there no longer can be ensured for a constant quality of the cast strand over the entire strand length.
There is also known to the art a method wherein a narrow or short side of the mold is pivoted about its lower edge in tilting relationship to the center of the mold, and thereafter the small side is then pivoted or rocked about its upper edge towards the center of the mold. To carry out these operations it is necessary to exert large forces upon the narrow or small sides of the mold, in opposition to the ferrostatic pressure, and there is an extremely great danger of forming fissures at the soft shell or skin of the cast strand during pivoting or rocking of the lower part of the short side towards the center of the mold. Also, reinforcement plates immersed in the steel melt only partially overcome this danger.